1. Field of the Invention
The present invention relates to an ultrasonic diagnostic apparatus for obtaining a biogenic tomogram by irradiating an ultrasonic pulse in vivo and receiving a reflecting wave which is reflected from a biogenic tissue.
2. Description of the Related Art
Hitherto, there has been put into practical use an ultrasonic diagnostic apparatus for obtaining a biogenic tomogram by irradiating an ultrasonic pulse in vivo and receiving a reflecting wave which is reflected from a biogenic tissue. Since the ultrasonic diagnostic apparatus can noninvasively diagnose the internal part of the biological material and thus has high safety therefor, this is an indispensable apparatus for a clinical medicine and is widely spread. In particular, the ultrasonic endoscope is used for diagnosing a case which can not be decided by a surface of the biological material and which needs to insert the ultrasonic diagnostic apparatus into the celom. This has increased the demand for the ultrasonic diagnostic apparatus.
FIG. 20 is a block diagram showing a constructional example of a conventional ultrasonic diagnostic apparatus of a mechanical scanning system.
As shown in FIG. 20, the ultrasonic diagnostic apparatus of the mechanical scanning system is provided with a controller 22 that a CPU 23 as control means controls. A motor driving circuit 3 is controlled in response to a timing signal of the controller 22, and a motor drive signal from the motor driving signal 3 causes the rotation of a motor 4 and a vibrator 5 which is mounted to a rotating shaft of the motor 4 at a center of the rotation.
The vibrator 5 supplies, to the controller 22, via a position detecting circuit 71 a synchronous signal outputted from the position detecting circuit 71 by the rotation of the vibrator 5, and which is synchronized with the timing signal, thereby emitting an ultrasonic pulse. A transmission signal generator 1 oscillates a transmission signal as a reference under the control operation of the controller 22. A transmitting amplifier 2 thereafter amplifies the oscillation signal to a necessary level. After that, the amplified signal is supplied to the vibrator 5, thereby emitting the ultrasonic pulse, for example, to the internal part of the biological material.
The vibrator 5 receives a reflecting wave which is reflected from the biogenic tissue. A receiving amplifier 6 and a band pass filter (labeled as a BPS in the figure) 7 remove an unnecessary signal component from the received signal. After a detecting circuit 8 detects the signal, the detected signal is amplified to a predetermined size by a GAIN/STC 9 as a variable amplifier capable of varying an amplification factor.
A reception signal outputted from the GAIN/STC 9 passes through a low pass filter (labeled as an LPF in the figure) 12, an A/D converter 13 converts the reception signal into a digital signal, and it is stored into a FIFO 14. The data stored in the FIFO 14 is coordinatetransformed by an address control 16 and a look-up table (LUT) 17 for coordinate transformation, and stored into a predetermined position in a memory 15.
The above operation is controlled by the controller 22 at a predetermined periodic interval until one rotation by the vibrator 5 ends. After storing the reception data of one rotation to the memory 15, the stored data is read out of the memory 15 by the reading-out operation of the address controller 16 and the read-out data is supplied to an interpolating circuit 18. In the interpolating circuit 18, an LUT 19 for interpolating process executes an interpolating process, and a video processing circuit 20 performs a process necessary for display after that. The processed signal is thereafter supplied to a monitor 21, thereby displaying a radial image based on the reception data.
FIG. 21 is a block diagram showing a constructional example of a conventional ultrasonic diagnostic apparatus of a mechanical scanning system in case of adding a linear display function to the ultrasonic diagnostic apparatus shown in FIG. 20.
In FIG. 21, the motor driving circuit 3 is controlled in response to the timing signal of the controller 22 and the vibrator 5 is rotated. Synchronously with the timing signal of the controller 22, the vibrator 5 receives and transmits an ultrasonic wave.
Only a predetermined signal is amplified and taken out of the reception signal by the receiving amplifier 6, BPF 7, detecting circuit 8, and GAIN/STC 9. The A/D converter 13 converts the taken-out signal to a digital signal and stored into the FIFO 14. The stores it data is coordinate-transformed by the address controller 16 and LUT 17 for coordinate transformation and stored to a predetermined position in the memory 15. The aforementioned operation is the same as that of the apparatus shown in FIG. 20, and conducted at a predetermined periodic interval until the end of one rotation of the vibrator 5.
After storing the reception data of one rotation to the memory 15, the stored data is read out of the memory 15 by the reading-out operation of the address controller 16 and the read-out data is supplied to the interpolating circuit 18. In the interpolating circuit 18, the LUT 19 for interpolating process executes the interpolating process for the supplied data, and the interpolated data is thereafter stored into a radial image memory 25a and a linear image memory 25b of an image memory 25 which is newly provided, based on a writing control by an image output controller 24. In this case, there is stored to the radial image memory 25a the same data as the data outputted to the video processing circuit 20 shown in FIG. 20. Additionally, there is stored to the linear image memory 25b data which corresponds to a tomogram of one frame formed by coupling data at an arbitrary portion that is designated by the radial image which is subjected to the interpolating process as much as a plurality of frames.
The image output controller 24 controls the operation for reading out the data stored to the image memory 25 by the radial image memory 25a and linear image memory 25b, based on an output mode of a selected image. Similarly to the foregoing apparatus, the read-out data is supplied to the video processing circuit 20, thereby performing the process necessary for display for the read-out data. The processed data is thereafter supplied to the monitor 21, which to thereby displays a radial image or a linear image based on the reception data, or an image corresponding to both of them.
Referring to FIGS. 20 and 21, when the rotational period of the vibrator 5 is different depending upon a connected scanner (ultrasonic endoscope), another system in which the address controller 16 is changed corresponds thereto. When connecting a scanner which mechanically drives a vibrator different from that in FIGS. 20 and 21 (such as sector scanning, 3D scanning, and scanning line density variation), another system in which the look-up table 17 for coordinate transformation and address controller 16 are changed corresponds thereto.
However, the FIFO 14, memory 15, address controller 16, and LUT 17 for coordinate transformation are necessary for coordinate-transforming the reception data which the A/D converter 13 converts into digital data by the conventional ultrasonic diagnostic apparatus. The interpolating circuit 18 and LUT 19 for interpolating process are also necessary for executing the interpolating process. Further, the CPU 23 is necessary for controlling the address controller 16 and controller 22. As mentioned above, the dedicated coordinate-transforming circuit and interpolating circuit are necessary, and since the processing circuits are high-speed arithmetic circuits, the circuits are made complicated. Because preparing data referred to in the processing step as the LUT for coordinate transformation and LUT for interpolating process, a dedicated memory for storing the data is made necessary, the circuit scale is increased, and thus costs also become expensive.
When changing the timing to fetch the reception data due to functional addition and changing the control to the receiving/transmitting unit, the exchange and correction of the controller 22 is needed and this causes a problem that the function cannot be added simply.
In order to cut out an arbitrary position of the radial image obtained by the coordinate transformation and interpolating process and generate the linear image by coupling the cut-out images, there are necessitated the linear image memory 25a and image output controller 24 for generating the linear image. The radial image and linear image are combined and displayed and, therefore, there are necessitated the radial image memory 25a and linear image memory 25b as the image memory 25 and the image output controller 24 for controlling the image outputs by the image output modes. Also necessitated are the dedicated processing circuit and the image storing memory which further have to be operated at a high speed, so that the circuit scale is increased and complicated, and costs are also made expensive in this case.
The period and the like of a position signal outputted from the position detecting circuit 71 are made different, depending upon the scan of a connected scanner (such as sector scanning, linear scanning, radial scanning, variation in rotational speed of the vibrator, 3D scanning, and scanning line density variation). Therefore, it is necessary to change the design of the controller 22 and the address controller 16 for controlling the FIFO 14 and memory 15, or provide a memory in the address controller 16 and controller 22 and prepare a parameter for timing change whose number corresponds to the scanning of the connected scanner. As explained above, in order to correspond to the different period and the like by the design change of the controller system including the controller 22 and the address controller 16, a substrate including a controller, etc. is exchanged unavoidably, the costs are made expensive, the connected scanner is restricted, and a function cannot be added. Further, to have a parameter whose number corresponds to the period of the position signal in the controller system, there are made necessary a device for control whose circuit scale is large and an external memory device, and this thus causes a problem that the costs are expensive.